7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Frank Sorenson commit 1dac61e2c29d1a71784604b48cf3b1234a65ec29 upstream. cifs_set_acl() validates ACL size using posix_acl_xattr_size(): 4 + (count * 8) // 4-byte header + 8 bytes per ACE cifs_do_set_acl() then calls posix_acl_to_cifs() to write the CIFS wire format into the same buffer: 6 + (count * 10) // 6-byte header + 10 bytes per ACE An ACL that passes the xattr-based check in cifs_set_acl() can overflow the heap when posix_acl_to_cifs() writes the larger CIFS format. Validate the CIFS format size against the remaining buffer space and USHRT_MAX before converting--data_count is __u16, so sizes above USHRT_MAX truncate the on-wire packet length, causing the server to apply a partial ACL. Replace MaxDataCount = 1000 with min(CIFSMaxBufSize, USHRT_MAX). Fixes: dc1af4c4b4721 ("cifs: implement set acl method") Cc: stable@vger.kernel.org Signed-off-by: Frank Sorenson Signed-off-by: Paulo Alcantara Signed-off-by: Greg Kroah-Hartman --- fs/smb/client/cifssmb.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) --- a/fs/smb/client/cifssmb.c +++ b/fs/smb/client/cifssmb.c @@ -3571,6 +3571,7 @@ int cifs_do_set_acl(const unsigned int x int rc = 0; int bytes_returned = 0; __u16 params, byte_count, data_count, param_offset, offset; + size_t cifs_acl_size, bytes_available; cifs_dbg(FYI, "In SetPosixACL (Unix) for path %s\n", fileName); setAclRetry: @@ -3590,8 +3591,7 @@ setAclRetry: } params = 6 + name_len; pSMB->MaxParameterCount = cpu_to_le16(2); - /* BB find max SMB size from sess */ - pSMB->MaxDataCount = cpu_to_le16(1000); + pSMB->MaxDataCount = cpu_to_le16(min_t(unsigned int, CIFSMaxBufSize, USHRT_MAX)); pSMB->MaxSetupCount = 0; pSMB->Reserved = 0; pSMB->Flags = 0; @@ -3603,6 +3603,15 @@ setAclRetry: parm_data = ((char *)pSMB) + offset; pSMB->ParameterOffset = cpu_to_le16(param_offset); + /* make sure we can fit the larger cifs_posix_aces in the buffer */ + cifs_acl_size = sizeof(struct cifs_posix_acl) + + (acl->a_count * sizeof(struct cifs_posix_ace)); + bytes_available = (CIFSMaxBufSize + MAX_HEADER_SIZE(tcon->ses->server)) - offset; + if (cifs_acl_size > bytes_available || cifs_acl_size > USHRT_MAX) { + rc = -E2BIG; + goto setACLerrorExit; + } + /* convert to on the wire format for POSIX ACL */ data_count = posix_acl_to_cifs(parm_data, acl, acl_type);